Apical membrane protein 1‐specific antibody profile and temporal changes in peripheral blood B‐cell populations in Plasmodium vivax malaria

Plasmodium falciparum‐specific antibodies tend to be short‐lived, but their cognate memory B cells (MBCs) circulate in the peripheral blood of exposed subjects for several months or years after the last infection. However, the time course of antigen‐specific antibodies and B‐cell responses to the relatively neglected parasite Plasmodium vivax remains largely unexplored. Here, we showed that uncomplicated vivax malaria elicits short‐lived antibodies but long‐lived MBC responses to a major blood‐stage P vivax antigen, apical membrane protein 1 (PvAMA‐1), in subjects exposed to declining malaria transmission in the Amazon Basin of Brazil. We found that atypical (CD19⁺CD10^?CD21^?CD27^?) MBCs, which appear to share a common precursor with classical MBCs but are unable to differentiate into antibody‐secreting cells, significantly outnumbered classical MBCs by 5:1 in the peripheral blood of adult subjects currently or recently infected with P vivax and by 3:1 in healthy residents in the same endemic communities. We concluded that malaria can drive classical MBCs to differentiate into functionally impaired MBCs not only in subjects repeatedly exposed to P falciparum, but also in subjects living in areas with low levels of P vivax transmission in the Amazon, leading to an impaired B‐cell memory that may affect both naturally acquired and vaccine‐induced immunity.